1. Field of the Invention
This invention relates to a strobe light. Specifically, the invention is directed to a strobe light that uses light emitting diodes.
2. Description of the Related Art
Aircraft operating at night utilize a variety of lights to attract the attention of other aircraft operating in the same airspace, in order to prevent collisions between aircraft. One such lighting system is the anticollision lighting system. A typical anticollision lighting system consists of flashing lights installed at several points on the aircraft to ensure that the lighted aircraft is visible to other aircraft operating in the vicinity. Anticollision lights are typically mounted on the aircraft""s upper and lower fuselage, the tail, and the wingtips.
Anticollision lights have previously been installed on aircraft for this purpose, but they suffer from several disadvantages. Prior anticollision lights commonly use incandescent lamps and flashers or xe2x80x9crotating beaconxe2x80x9d mechanisms to create an attention-getting pattern of light. However, flashers and rotating beacons suffer from limited life due to lamp burn-out and mechanism wear. The amount of light emitted from these anticollision lights is also relatively low, affording limited attention-getting light at distances from the aircraft.
Many flashers and rotating beacon lights have been replaced by xe2x80x9cstrobexe2x80x9d lights owing to the strobe""s brilliant, sharp flash and high light output. Strobe lights also offer increased service life over flashers and rotating beacons due to the lack of incandescent lamps and moving parts. In a typical strobe lighting system, aircraft electrical power is converted to a high-voltage direct current (DC) potential. The high-voltage DC is applied to a xenon gas lamp, which is xe2x80x9ctriggeredxe2x80x9d to arc between its anode and cathode terminals by a second voltage which is applied to the lamp""s grid terminal. Although more reliable than flashers and rotating beacons, prior strobe lights still suffer from a relatively short service life due to degradation of the strobe""s electronic components as a result of the continuous high-voltage charge and discharge cycles associated with each flash of the lamp.
Light emitting diodes (xe2x80x9cLEDsxe2x80x9d) have previously been utilized for aircraft lighting, such as Fleischmann U.S. Pat. No. 6,203,180. However, Fleischmann teaches the use of light emitting diodes for interior cabin illumination, rather than exterior anticollision lighting, and does not address the attention-getting characteristics necessary for strobe lights. Anderson U.S. Pat. No. 4,912,334 discloses the use of light emitting diodes for anticollision lighting during covert aircraft operations. However, the requirements of anticollision lighting for covert and non-covert operations differ considerably. Covert operations require the use of infra-red emitting diodes visible only to night vision imaging equipment. Further, the desired light output of covert anticollision lighting is of a comparatively low level and is intended to provide awareness only to other xe2x80x9cfriendlyxe2x80x9d aircraft operating in the immediate vicinity of the lighted aircraft. In contrast, the goal of non-covert visible-light anticollision lighting is to provide sufficient notice to other aircraft at significant distances from the lighted aircraft in time to avoid collisions or emergency evasion procedures. There is a need for a strobe light which provides a sharp, bright pulse of visible light that can be seen at the significant distances desired for non-covert strobe anticollision lighting and which provides long operating life in the harsh aircraft environment.
This invention is directed to a strobe light that provides the sharp, bright pulse of light desired for non-covert anticollision lighting without resorting to a xenon lamp and a complex high-voltage power converter.
Specifically, the present invention includes a multitude of solid-state light sources, preferably light emitting diodes. The LEDs are arranged about the circumference of a disk to form a xe2x80x9clight ringxe2x80x9d having 360-degree coverage for light emission. Light rings may be stacked if desired in order to produce the desired photometric output characteristics. When the LEDs are arranged in an array configuration, the LEDs can provide beneficial attributes such as inherent redundancy. If one or more of the LEDs in the array were to fail, the remaining LEDs will continue to operate.
The LED strobe light may include a housing structure to contain internal components of the LED strobe light. The housing may include mounting points or a mounting flange to facilitate installation of the LED strobe light onto the aircraft. The housing and mounting arrangement may be shaped to permit replacement of a prior flashing light, rotating beacon, or xenon strobe with the LED strobe, without the need to modify the structure of the aircraft. The LED strobe may also incorporate a lens to protect the components from the elements.
Electrical power from the aircraft is connected to a control circuit which conditions the voltage and current to a level compatible with the LEDs. The control circuit may be mounted inside the housing structure, or may be located remotely. The control circuit provides sufficient electrical power to activate the LEDs while preventing over-driving of the LEDs. The control circuit also regulates the on-off timing of the LEDs, applying an electrical pulse to the LEDs approximately once per second, to produce a regular burst of light.
The control circuit may optionally provide temperature compensation for stabilized strobe light brightness with variations in ambient temperature. The control circuit may also optionally include self-diagnostic capabilities. For example, the control circuit may monitor the strobe light for fault conditions and alert the flight crew by means of an electrical output signal connected to a warning indicator in the cockpit. Alternatively, the fault signal provided by the control circuit could be connected to the aircraft""s maintenance computer. Fault notification could also be made to the operator by altering the strobe light""s output characteristics in a manner calculated to attract the operator""s attention, such as altering the flash rate.
Servicing of the LED strobe light may be simplified with the inclusion of optional control circuit bench-test diagnostic features. For example, the strobe light could be configured with the capability to illuminate the LEDs dimly in a constant-on mode to facilitate visual inspection of the LED strobe for failed LED elements without the need for protective eyewear. In addition, one or more of the LEDs could be configured to transmit status and diagnostic data while in a bench-test mode by emitting a regular series of dim flashes. The number of flashes would correspond to pre-programmed diagnostic conditions. The status and diagnostic LEDs could also be used to optically couple serial data, such as fault codes, from the control circuit to a maintenance computer.
Accordingly, it is an object of this invention to provide a strobe light for use on an aircraft that provides long operating life and the necessary light intensities without resorting to xenon lamps or high-voltage power supplies. This invention overcomes the drawbacks of prior strobe lights through the use of light emitting diodes.
The present invention comprises a strobe light for use on an aircraft, comprising: an electrically insulative, thermally conductive base; at least one electrically conductive ring, placed over said base; at least one light ring comprising a plurality of light sources arranged about the circumference of an electrically insulative, thermally conductive disk, said light ring being placed over said electrically conductive ring; an electrically conductive cover, placed over said light ring; a control circuit for transmitting regular pulses of electrical current between said cover and said base; and means for securing together said base and said cover.
These and other features will become better understood with reference to the following description, appended claims, and accompanying drawings.